Field of the Invention
The present invention relates to broad spectrum preservation blends. In particular, the present invention relates to preservation blends that incorporate benzyl alcohol, salicylic acid, sorbic acid and an additive. The additive is selected from the group consisting of 1,3-propanol, dehydroacetic acid, glycerin and a combination thereof. The preservation blends of the invention are stable at low temperatures and have a high efficacy against a broad spectrum of microorganisms at a wider than expected pH range.
Brief Description of Art
Preservatives have wide applications in fields like personal care, industrial, health and hygiene, pharmaceutical and wood protection. Preservatives can be a single agent or a blend of multiple agents.
Ideally, a preservative has broad-spectrum activity against all types of microorganisms at various pH levels. The preservative should also have high efficacy so that a minimum amount of the preservative can be used to save cost and to avoid or reduce any possible adverse effects caused by the preservative. Also, it is desirable that the preservative is stable to any changes in temperature encountered during manufacturing, packaging, and shipping as well as during storage of the preservative. Further, an ideal preservative is physically and chemically compatible with ingredients of different application systems so that one preservative can suitably be incorporated in various products.
Benzyl alcohol, salicylic acid and sorbic acid are known preservative agents, but individually they are of limited usefulness with regards to broad spectrum activity because these actives are known to have poor activity at more neutral and alkaline pH. In addition, salicylic acid and sorbic acid can be difficult to solubilize at high concentrations, thus making an effective concentrate difficult to achieve.
Certain preservative blends containing either one or more of benzyl alcohol, salicylic acid, or sorbic acid are known. For example, Optiphen® BSB-N from ISP is a combination of benzoic acid, sorbic acid and benzyl alcohol and glycerin. Sharomix® 705 from Sharon Laboratories is a liquid blend of benzyl alcohol, benzoic acid, sorbic acid and dehydroacetic acid. However, the application of these preservatives is limited because they are only suitable for low pH systems (up to pH 6.5).
US patent application publication 2009/0123577 to Air Liquide Sante, the disclosure of which is incorporated herein in its entirety, discloses a liquid concentrate for preserving cosmetics including a carboxylic acid component (A) containing at least two carboxylic acids selected from benzoic acid, propionic acid, salicylic acid, sorbic acid, 4-hydroxybenzoic acid, dehydroacetic acid, formic acid and 10-undecylenic acid; an alcohol component (B) selected from phenoxyethanol, benzyl alcohol. Unfortunately, the preservative concentrate disclosed in the publication uses up to 40% of water as solvent. As water freezes at 0° C., this may cause difficulties in handling the disclosed concentrate at low temperatures. Further, the disclosed preservatives are suitable for use in systems having a pH of less than 7, in particular less than 6.
Accordingly, there is a continuing need for another preservative, which is stable at low temperatures, and which has a high efficacy against a broad spectrum of microorganisms at a wide pH range. The present invention provides one answer to that need.